Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [dsp]

Questions about digital signal processing, whether of RF, audio, or digital signals. For RF, consider [software-defined-radio].

Use this tag when the topic includes Digital Signal Processing. This can be either RF signals or audio signals, or perhaps post-processing like decoding of protocols.

is a perfect example of DSP-based radio. Similarly, recording of signals for later processing (like manipulating satellite imagery to assign false colors and the like) could be considered to fall under this category.

37 questions
9
votes
1 answer

Calculating the signal-to-noise ratio for CW (Morse Code) signals?

How is the signal-to-noise ratio for received CW and QRSS CW (and/or other ultra narrow-band DSP digital modes) typically computed? e.g. What noise bandwidth should be used to measure the spectrum power against the narrow CW "on" signal power?…
hotpaw2
  • 13,116
  • 6
  • 40
  • 72
7
votes
4 answers

How can quadrature mixing adjust the phase of all frequencies by the same amount? Can it be done in the digital domain?

This came up in some feedback I got when I tried to answer What is IQ in the context of SDRs? and revealed some of my own misunderstanding. Initially, I gave an answer something like (paraphrasing): You could collect I/Q data by taking a second…
natevw - AF7TB
  • 7,219
  • 2
  • 23
  • 58
6
votes
2 answers

Can an ultra-wideband system transfer data at high speed without precise clock synchronization?

Recently, ultra-wideband technology has been in the news again. From the Wikipedia article: UWB transmissions transmit information by generating radio energy at specific time intervals and occupying a large bandwidth, thus enabling pulse-position…
natevw - AF7TB
  • 7,219
  • 2
  • 23
  • 58
5
votes
3 answers

Detecting signals using statistics

I have sampled a section of spectrum every few Hz. I have mean, standard deviation, and range data for every frequency sampled (and I can gather more statistics if necessary). I've sampled for several seconds before storing the spectrum…
Ken - Enough about Monica
  • 600
  • 2
  • 14
5
votes
1 answer

What does a receiver's noise reduction function do?

Some receivers contain a noise reduction button or function. What does this noise reduction do? Is there more than one type of noise reduction? How does the circuit or software know what part of the signal to reduce as noise and what part to not…
hotpaw2
  • 13,116
  • 6
  • 40
  • 72
4
votes
2 answers

Why does beamforming bring more power to the received desired signal?

Consider a normal array model with $N$ element. The output of the array is given by, $$\mathbf{y}=\mathbf{w}^H\mathbf{x}=\mathbf{w}^H\mathbf{as}$$ where $\mathbf{a}=[a_1,...,a_N]^T=\in\mathbb{C}^{N\times 1}$ is the manifold of the desired signal (I…
tyrela
  • 145
  • 6
4
votes
2 answers

Problem with sample rate

So I am working on a project that involves me to check real time difference between samples.I am fairly new to this so after a bit of researching I wrote a simple python script for it, here is the script. Here is the script: import time from rtlsdr…
RasenRhino
  • 43
  • 4
4
votes
1 answer

Modeling a regenerative receiver

What is the signal processing model of a simple regenerative or super-regenerative receiver? Is it just a linear 2-pole IIR filter with gain? How does a single regen control knob control both selectivity and gain? What causes the…
hotpaw2
  • 13,116
  • 6
  • 40
  • 72
4
votes
4 answers

Understanding how quadrature heterodyning captures information from negative frequencies

The way I understand how SDR works, there is a receiver input, generally connected to an antenna pulling in signals from the ether. That input is connected to two mixers (linear multipliers), being mixed with the same LO frequency in both mixers,…
KevinHJ
  • 215
  • 1
  • 4
4
votes
1 answer

Relative computational requirement for various digital modes?

What might be the relative computational performance requirements for the various popular digital modes? (FT, JT, WS, PSK31, etc.) I seem to recall FSK modulation/demodulation being done with 1 or so MHz 8-bit CPUs. By what factor or magnitude have…
hotpaw2
  • 13,116
  • 6
  • 40
  • 72
3
votes
1 answer

Implementing a BPSK and 4-FSK transmitters in GnuRadio (GRC) with USRP?

Currently trying to transmit a BPSK and a 4-FSK(MFSK) signal via GRC using USRP, I have two attempts at it but don't seem to be going anywhere. Still fairly new to GRC. For the BPSK, how will this signal appear on the spectrum analyzer? I have seen…
lceans
  • 55
  • 5
3
votes
1 answer

Turning raw APT data into an image

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out of a WAV file representing the signal received…
CL40
  • 153
  • 4
3
votes
2 answers

What is Spectral Subtraction for noise reduction?

I previously asked a general question about noise reduction, but none of the answers mentioned this specific method or algorithm. (the noise reduction button on some radios and DSP software seems to enable spectral subtraction, rather than just…
hotpaw2
  • 13,116
  • 6
  • 40
  • 72
2
votes
1 answer

Device that plays only the audio component of a TV signal

Some radios have a TV dial, such as the Tecsun R-909T. But before purchasing, I tried to find a video demonstration of his work. I was confused by the fact that the work of a conventional radio is shown, but there is practically no work of the TV…
dtn
  • 121
  • 3
2
votes
0 answers

Why the Receiver Sensitivity theoretical value doesn't match its experimental value when using USRP B200mini in GNU Radio?

I'm using a USRP B200mini SDR card for my GNU Radio energy detector project. I wanted to measure its Receiver Sensitivity ($RS$) experimentally and compare the experimental value to the theoretical value. Assume the minimum needed Signal to Noise…
HadK
  • 21
  • 1
1
2 3